It hides caption bar, sizes everything down a bit (or at least it looks like it does), and (very important while reading larger articles) there Â´s a full-screen option, so the browser takes the whole screen all the bars,menus are then set to auto-hide."

I got one better -- get the add-on called "Tiny Menu". The entire menu bar is replaced by a single drop down, and you can move all of the navigation elements to the same bar that previously held File/Edit/etc, eliminating a bar completely.

It hides caption bar, sizes everything down a bit, and (very important while reading larger articles) there Â´s a full-screen option, so the browser takes the whole screen all the bars are then set to auto-hide.